. Sheet metal workers' manual; a complete, practical instruction book on the sheet metal industry, machinery and tools, and related subjects, including the oxy-acetylen welding and cutting process . le round in form withflaring sides, or an article having an irregular shape, itis highly important to make a full-sized drawing and todevelop the patterns. This necessitates operations withthe drafting board and drawing instruments, which willbe taken up later in this course. After the pattern isdeveloped on detail paper, it may be transferred to thesheet metal and the work of construction begun. M
. Sheet metal workers' manual; a complete, practical instruction book on the sheet metal industry, machinery and tools, and related subjects, including the oxy-acetylen welding and cutting process . le round in form withflaring sides, or an article having an irregular shape, itis highly important to make a full-sized drawing and todevelop the patterns. This necessitates operations withthe drafting board and drawing instruments, which willbe taken up later in this course. After the pattern isdeveloped on detail paper, it may be transferred to thesheet metal and the work of construction begun. Methods of Transfer.—There are several methods oftransfer in use, depending on the nature of the materialand the shape of the pattern. For the more expensivematerials, such as copper, brass, and German silver, thepatterns and designs are transferred to the metal bymeans of carbon paper in the following manner: The carbon paper is laid upon the face of the materialwith the face or glossy surface touching the metal; thepattern is carefully placed over the carbon paper andheld in position by small weights; then with a hard pen-cil, stylus, or pointed tool firmly trace over the lines of the 151. Figure 138.—Simple Patterns, or Templates. Arrows Show ProperDirection to Cut Metals with the Shears. SHEET METAL WORK AND PATTERN DRAFTING 153 drawing. This will give a print of the pattern on thebright metal. After obtaining a good impression, thecarbon lines may be fixed on the metal by tracing overthem with a steel scratch awl. Another method of transfer is used for the cheapermaterials, such as tin plate, zinc, black iron, and gal-vanized iron. The process is as follows: Place the draw-ing paper directly on the metal, then go over the outlineof the pattern with a sharp tapering prick punch, tappingit lightly with a small hammer, making slight indenta-tions on the metal at the principal points of the method will be used throughout this course, and isin general use in the
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Keywords: ., bookcentury1900, bookdecade1910, bookidsheetmetalwo, bookyear1918
